Routing is a communications network function that is performed to advance a telephone call from an origination point to a destination point. Such a routing function is, therefore, at the heart of the architecture, design and operation of a communications network. Most routing functions were initially designed to route what is commonly referred to as "Plain Old Telephone Service" (POTS) calls. Thereafter, to meet customer and competitive demands, communications networks began offering additional services, such as, for example, (a) digital seduces for transporting data, (b) very low blocking services to ensure with a high level of probability that associated service calls are routed to their destinations during times of network congestion, and (c) the well-known 800 and 900 number services. The introduction of a new service is usually accompanied by a change in the underlying routing function so that telephone calls associated with the new service may be properly routed to their respective destinations. However, over time, each such change may cause the underlying network routing function to become complex and unwieldy to administer, thereby making it difficult to further change the routing function to accommodate other new services.